As a method for obtaining a vinyl polymer based on polymerization of a vinyl monomer, a radical polymerization method is conventionally known. The radical polymerization method has a disadvantage that it is generally difficult to control the molecular weight of a vinyl polymer to be obtained.
Furthermore, there is also a disadvantage that, as the vinyl polymer to be obtained is a mixture of compounds with various molecular weights, it is difficult to obtain a vinyl polymer with narrow molecular weight distribution.
Specifically, even when the reaction is controlled, the ratio (Mw/Mn) between weight average molecular weight (Mw) and number average molecular weight (Mn) can be only reduced to 2 to 3 or so.
As a method for overcoming the above disadvantages, a living radical polymerization method has been developed since 1990. Namely, according to the living radical polymerization method, it is possible to control the molecular weight and also possible to obtain a polymer with a narrow molecular weight distribution.
Specifically, since it is possible to obtain easily a polymer which has Mw/Mn of 2 or less, the method receives great attention as a method for producing a polymer that is used for a cutting edge field like nano technology (see, Patent Literature 1, for example).